Hook-on sharpening attachment



Sept. 22, 1964 R. E. SCHNEIDER 3,149,444

uoox-on SHARPENING ATTACHMENT 'iled Sept. 17, 1962 2 Sheets-Sheet 1 Robe/"f E Schneider INVENTOR Fig.5 BY W Q. M

ATTORNEY P 1964 R. E. SCHNEiDER 3,149,444

HOOK-0N SHARPENING ATTACHMENT Filed Sept. 17, 1962 2 Sheets-Sheet 2 1 27a 1 ===I I 24 /8 28b 280 I9 25 as a 28 2/ 20 15 I2 1/ Fig 8 Roberf E. Schneider INVENTOR %2.. Q. MATTORNEY' United States Patent C) 3,149,444 HO-QK-ON SELKRPENING ATTACHI/KENT Robert E. Schneider, 244 W. Her-mine, San Antonio, Tex. Filed Sept. 17, 1962, Ser. No. 223,924 11 Claims. (Cl. 51-249) The present invention relates to apparatus for grinding straight edges on knives of woodworking machines, as for example, jointers or the like, and more particularly to apparatus which is detachably attached to the supporting table of the machine and is used with conventional grinding devices for accurately cutting the edges of the knives while the same are secured in the cutterhead of the machine.

An object of the present invention is the provision of apparatus for grinding blades of jointers and the like which obviates the necessity of removing the blades and/ or the cutterhead from the machine.

Another object is to provide apparatus which utilizes equipment presently available in every woodworking shop to sharpen straight cutting edges of knives of woodworking machines.

A further object is to provide a single size apparatus which is operative on all sizes of jointers or the like.

Still another object of the invention is to provide lade grinding apparatus for sharpening straight edges on blades parallel to the work table of the machine without leveling and time consuming adjusting operations.

Yet another object is to provide for accurately positioning and locking the cutterhead in position thereby assuring the same clearance on each blade in the cutterhead.

A still further object is the provision of a simple, highly-efiicient, durable and accurate apparatus of lightweight construction which can be quickly positioned an is used with existing equipment to accurately sharpen the blades of a jointer or the like.

Other objects and features of the invention will become apparent to those skilled in the art as the disclosure is made in the following detailed description of preferred embodiments of the invention as illustrated in the accompanying sheets of drawing in which:

FIG. 1 is a perspective view of the base plate of the subject invention attached to the tables of a jointer preparatory to sharpening the blades in the cutterhead;

FIG. 2 is a bottom plan view of the base plate illustrated in FIG. 1;

FIG. 3 is a sectional view taken on the line 33 of FIG. 2 looking in the direction of the arrows;

FIG. 4 is a sectional view taken on the line 44 of FIG. 2 looking in the direction of the arrows;

FIG. 5 is a sectional view of a portion of the base plate of FIG. 1 showing the apparatus for locking the cutterhead of the jointer in position;

FIG. 6 is a perspective view of a guide plate for use with a router;

FIG. 7 is a view partly in section showing a router being used with the assembly of FIGS. 1 and 6;

FIG. 8 is a perspective view of a guide plate for use with a portable power saw having a grinding attachment; and

FIG. 9 is a view partly in section showing a power saw having a grinding attachment being used with the assembly of FIGS. 1 and 8.

Referring now to the drawings, wherein like reference characters desginate like or corresponding parts throughout the several views, there is shown in FIG. 1 a conventional jointer 19 having fully controlled and adjustable infeed and outfeed tables 11 and 12, respectively. Hand wheels 11a and 12a are provided for operating the mechanism of the machine for varying the height of said tables.

3,149,444 Patented Sept. 22, 1964 Although a jointer is illustrated in FIG. 1 of the drawings, it is to be understood that the invention is not restricted thereto but will also function on any other type of cutting machine having straight edge cutting knives, where the edges of said knives are parallel to the surface of the work tables.

The rip fence, guard and additional attachments on the work table of the machine are to be removed prior to sharpening the knives 13 in the cutterhead 14.

A base plate 15 which is of generally rectangular configuration is detachably attached to the jointer 10 in a manner hereinafter to be described in detail, said plate 15 includes a rectangular slot 16 which is off-center and aligned with respect to the longitudinal plane of the apparatus. -In the preferred embodiment of the invention base plate 15 is constructed of cast aluminum or magnesium, plywood or any other suitable material and is approximately twenty-four inches in length by approximately nineteen inches in width. The recess 16, hereto fore described, is approximately eighteen inches in length by two and one-quarter inches in width. When said plate is used with apparatus hereinafter to be described the blades of any jointer or the like ranging from four inches to sixteen inches in width may be sharpened.

A guide fence 17 is adapted for sliding movement on surface 15a and consists of a rectangular bar 18 corresponding approximately in length to the base plate 15. The undersurface of bar 18 is pivotally connected adjacent its extremeties to arms 1941-1917 in a conventional manner, said arms being mounted for rotation on pins 20 which insert into plate 15. A screw 21 is threaded into an extremity of arm 19a and bears against surface 15a to lock the guide fence 17 in position.

As best seen in FIG. 1, the lower surface of plate 15 includes an indented portion 15b, said portion corresponds to a fixed, predetermined diiierence between the heights of the infeed and outfeed tables, 11 and 12, respectively, said recessed portion 15b extends to a shoulder 15c aligned with respect to side 16b of slot 16 as best seen in FIG. 2.

Referring again to FIG. 2 of the drawings, a plurality of attaching members 22a-22d are adjustably mounted in a conventional manner in recessed portions 15d (see FIG. 3) in the bottom surface of the base plate 15 adjacent sides 161146]; of slot 16 whereby the hooks 23 of said attaching members extend into slot 16 and project downward and outward.

The base plate 15 is to be positioned on the tables of the jointer 10 so that the hooks 23 of members 22a-22b attach to the edge 11!) of the infeed table 11 of the jointer (see FIGS. 7 and 9). The books 23 of members 22c22d are positioned adjacent the edge 12b of outfeed table 12 and by adjusting hand wheel 12a a vise-like grip is formed between members 22a-22b and 220-2201, respectively, locking the base plate 15 to the tables 11- 12 of the jointer. Attaching members 22a22d are preferably constructed of spring steel or the like.

In order to assure the identical positioning of the blades or knives during each grinding operation, a stop 24 is adjustably mounted in a recess in the bottom surface of base plate 15 intermediate members 22a22b. As best seen in FIG. 4 the free end of said stop is offset and extends into the slot 16, said offset portion 24a is adapted to engage the blades 13 in the cutterhead 14. In a modification of the invention the stop is a flat, rectangular bar (see FIGS. 7 and 9); in either case, however, the stop 24 preferably is constructed of spring steel or the like, the end 24a thereof will ride over the respective blades as the cutterhead 14 is turned counterclockwise for moving the respective blade into grinding position.

In a further modification of the invention (not shown) an elongated slot and recessed portion, adapted to receive the fastening device for the stop 24, is provided in the plate 15 whereby said stop may be adjustable while the plate is attached to the machine. Specifically, the stop may be accurately positioned relative to the blades in the cutter-head, said fastening device passes through said elongated slot and is secured in said recessed portion in a conventional manner.

It is essential that the cutterhead 14 be held stationary during the grinding of each blade and that each blade on the cutterhead be moved to the same grinding position as the next preceding blade in order that the clearance or bevel of the cutting edge will be the same on every blade of the cutterhead. It is also desirable that each time the blades are ground the same preferred bevel will be maintained thereon.

When a blade is in grinding position and end 24a of stop 24 engages said blade in the manner heretofore de scribed and the cutterhead is to be locked against rotation. The locking device 25 consists of a base 25a positioned in a recess 15e in the bottom surface of the plate 15 and attached thereto in a conventional manner and includes a vertically depending portion 25b having a plurality of threaded apertures into any one of which is threaded the shank portion 26a of a setscrew 26, the shank 26a preferably terminating in a rounded end 26b. End 26b of the shank bears against the belt 27 (see FIG. 5) of the cutterhead drive pulley below center. When setscrew 26 is placed in the threaded aperture which aligns with the belt 27 on the cutterhead drive pulley and the setscrew 26 is tightened, end 26b bears against belt 27 exerting a back pressure on the cutterhead 14 forcing the blade 13 against end 24a of stop 24 to lock the cutterhead in position. Plate is provided with a recessed portion 15 adjacent the cutterhead drive pulley and belt 27 to permit clearance thereof, as best seen in FIG. 5.

There is shown in FIG. 6 a guide plate 28 containing an aperture 28:: into which the base of a router inserts. In the preferred embodiments of the invention, the guide plates of FIGS. 6 and 8 are constructed of plywood or other suitable material and are approximately seventeen and one-half inches in length and approximately twelve inches in width.

A conventional router 29 consisting of a motor 290 which screws into a base 2% for depth adjustment inserts into aperture 28a of plate 28. An emery grinding wheel 30 attaches to spindle 33 of the motor 29a.

After the cutterhead has been locked in position in the manner heretofore described in detail, guide plate 28 is placed on plate 15 in such a manner that the lower surface of grinding wheel 36 of the router will grind on the blade 13 only and not on the cutterhead 14. Referring now to FIG. 7, bar 18 of guide fence 17 is placed against side 28b of plate 28 and screw 21 (also see FIG. 1) is tightened, locking the guide fence in position. The motor 29a of the router is rotated so that the grinding wheel 30 just touches the blade as only a very light grinding is required to sharpen the blades of a jointer. The plate 28 containing the router 29 is then backed oif until the grinding wheel 30 is clear of the blade, the router motor is started and by pushing the router forward slowly, the guide fence 17 maintains the proper direction of movement and the blade is sharpened in a true line with the jointer table. This cycle of operations may be repeated until the blade is satisfactorily sharpened.

After the first blade is ground, setscrew 26 is loosened; as the cutterhead 14 is turned counterclockwise the end 24a of the stop 24 rides over the succeeding blade and engages said blade; the setscrew is then tightened thereby locking the cutter head in grinding position preparatory to sharpening said succeeding blade. Each blade is in turn sharpened in this manner until all the blades contained in the cutterhead are sharpened.

There is shown in FIG. 7 a guide plate 31 containing an essentially rectangular aperture 31a which conforms to the shape of the base of a conventional portable power saw 32 (see FIG. 9) having a calibrated depth adjustment 32a and preferably a one-half inch emery wheel 32b positioned on the arbor of said saw. The side 31!; of said aperture is to be aligned with respect to side 31c of said plate at an angle of approximately 75 so that the emery wheel 32b grinds the blade 13 from the edge towards the heel of said blade. Referring again to FIG. 9 of the drawings, the plate 31 is placed on plate 15 and adjusted so that the emery wheel 3212 will grind on the blade 13 only and not on the cutterhead 14. Bar 18 is then placed against side 31c of guide plate 31 and screw 21 (see FIG. 1) is tightened, locking the guide fence 17 in position. T he depth adjustment 32a allows the positioning of the emery wheel 32b so that said wheel just touches the blade as only a very light grinding is required to sharpen the jointer blades. The guide plate 31 containing the saw 32 is then backed off so that the wheel 32b is clear of the blade 13, the motor is started and by pushing the saw forward slowly, the guide fence 17 maintains the proper direction of movement and the blade is sharpened in a true line with respect to the jointer tables. This cycle of operations is repeated until the blade is satisfactorily sharpened. Each succeeding blade is to be sharpened in a like manner.

it should be understood, of course, that the foregoing disclosure relates to only preferred embodiments of the invention and that numerous modifications or alterations may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

l. A sharpening attachment for machines containing knives having straight cutting edges comprising a base plate, a slot in said base plate, means attaching said base plate to said machine, said base plate including guide means, a second plate having an aperture, said second plate positioned on said base plate and abutting said guide means, and a grinding device inserting into said aperture and bearing against said knives.

2. A hook-on sharpening attachment for machines having straight cutting edges parallel to the work surface of said machine consisting of a base plate, a slot in said base plate, guide means attached to said base plate, a second plate having an aperture, said second plate overlying said base plate and abutting said guide means, and a grinding device inserting into said aperture and bearing against said straight cutting edges of said machine.

3. A hook-on sharpening attachment for machines having straight cutting edges positioned in a cutterhead parallel to the work table consisting of a base plate having an elongated slot, means attaching said base plate to said machine, adjustable guide means connected to said base plate, a second plate having an aperture, said second plate positioned on said base plate and abutting said guide means, and a device having a grinding edge inserting into said aperture and bearing against said cutting edges of said machine.

4. A hook-on sharpening attachment for machines having straight edge cutting knives positioned in a cutterhead comprising a base plate, a slot in said base plate, means attaching said base plate to said machine, adjustable guide means attached to said base plate, a second plate having an aperture, said second plate overyling said base plate and abutting said adjustable guide means, a router including a grinding wheel, said router inserting into said aperture, said grinding wheel bearing against said cutting knives.

5. A hook-on sharpening attachment for machines having straight edge cutting knives positioned in a cutterhead comprising a base plate, a slot in said base plate, means attaching said plate to said machine, adjustable guide means attached to said base plate, a second plate having an aperture, said second plate overlying said base plate and abutting said adjustable guide means, a power saw including a grinding wheel, said saw inserting into said aperture, said grinding wheel bearing against said cutting knives.

6. A hook-on sharpening attachment for machines having straight edge cutting knives positioned in a cutterhead, said edges being parallel to the work surface of said machine consisting of a base plate, said plate including an elongated slot, means attaching said base plate to said machine, adjustable guide means attached to said base plate, means for accurately positioning said cutting edges preparatory to sharpening and means for maintaining said cutterhead in position, a second plate having an aperture, said second plate positioned on said base plate and abutting said guide means, and a router including a grinding wheel, said router inserting into said aperture, said grinding Wheel bearing against said cutting edges of said knives.

7. A hook-on sharpening attachment for machines having straight cutting edges positioned in a cutterhead comprising a base plate, an elongated slot in said base plate, adjustable guide means attached to said base plate, a second plate including an aperture, said second plate positioned on said base plate and abutting said guide means, said base plate including means for positioning and locking said cutternead and a grinding device inserting into said aperture and bearing against the cutting edges of said machine.

8. A sharpening attachment for machines containing knives having straight cutting edges comprising a base plate, means attaching said base plate to said machine, means in said base plate for accurately positioning said knives preparatory to sharpening and means for main taining said knives in position, guide means attached to said base plate, an elongated slot in said base plate, a second plate having an aperture, said second plate positioned on said base plate and abutting said guide means, and a grinding device inserting into said aperture and bearing against said knives.

9. A hook-on sharpening attachment for machines having straight cutting edges positioned in a cutterhead parallel to the work table comprising a base plate having an elongated slot, means attaching said base plate to said machine, adjustable guide means connected to said base plate, adjustable means in said base plate for accurately positioning said cutting edges preparatory to sharpening and means for maintaining said cutterhead in position, a second plate having an aperture, said second plate positioned on said base plate and abutting said guide means, and a device having a grinding edge inserting into said aperture and bearing against said cutting edges of said machine.

10. A hook-on sharpening attachment for machines having straight cutting edges positioned in a cutterhead comprising a base plate having a slot, means attaching said base plate to said machine, adjustable guide means connected to said base plate, means in said base plate for positioning said cutting edges preparatory to sharpening, means in said base plate for maintaining said cutterhead in position, a second plate having an aperture, said second plate positioning on said base plate and abutting said guide means, and a device having a grinding edge inserting into said aperture and bearing against said cutting edges of said machine.

11. A hook-on attachment for machines comprising a base plate, an elongated slot in said base plate, means attaching said base plate to said machine, adjustable guide means attached to said base plate, a second plate having an aperture, said second plate positioned on said base plate and abutting said guide means.

References Cited in the file of this patent UNITED STATES PATENTS 1,193,295 Perkins Aug. 1, 1916 2,347,800 Sjostrand May 2, 1944 2,620,606 Dvorak Dec. 9, 1952 2,729,923 Durst Jan. 10, 1956 2,864,210 Mann Dec. 16, 1958 2,944,376 Buttke July 12, 1960 

11. A HOOK-ON ATTACHMENT FOR MACHINES COMPRISING A BASE PLATE, AN ELONGATED SLOT IN SAID BASE PLATE, MEANS ATTACHING SAID BASE PLATE TO SAID MACHINE, ADJUSTABLE GUIDE MEANS ATTACHED TO SAID BASE PLATE, A SECOND PLATE HAVING AN APERTURE, SAID SECOND PLATE POSITIONED ON SAID BASE PLATE AND ABUTTING SAID GUIDE MEANS. 